1. Field of the Invention
The present invention relates to a method for controlling a cell reselection and a terminal to perform the method, and more particularly, to a method for controlling a cell reselection that may reduce the risk of a ping-pong phenomenon during the cell reselection process, and a dual mode terminal to perform the method.
2. Discussion of the Background
A Universal Terrestrial Radio Access Network (UMTS) terminal supporting Wideband Code Division Multiple Access (WCDMA) and a Global System for Mobile communications (GSM) performs a handover or reselection of a cell with a high priority in an area where two types of Radio Access Technologies (RAT) both exist. As used in this application, the term “terminal” and “dual mode terminal” will refer to a mobile communication terminal capable of supporting two different radio access technologies, such as WCDMA and GSM.
Although a handover during a call is controlled by the network, cell reselection in an idle state may be determined by a terminal itself and is not controlled by the network. Accordingly, if a terminal in an idle state is located in an area where a WCDMA cell and a GSM cell both exist, the terminal may reselect the WCDMA cell or the GSM cell that satisfies a predetermined condition.
When a WCDMA network, which has different Location Area (LA) codes with respect to an identical Public Land Mobile Network (PLMN) due to the cell reselection, is obtained, and a location registration is attempted but fails, a terminal may perform a PLMN reselection for retrieving different LAs with respect to an identical PLMN regardless of a cell reselection algorithm and regardless of whether a network selection mode is automatic or manual according to a 3rd Generation Partnership Project (3GPP) Technical Specification (TS) 23.122 standard. In this instance, although a GSM cell could be obtained, the same WCDMA network may be obtained again according to the cell reselection, even though the location registration failed once.
When a location registration fails in a manual mode due to a particular reason, an attempt to retrieve a new LA may be made despite a manual mode based on the 3GPP TS 23.122 standard. Accordingly, a terminal retrieves another LA with respect to an identical PLMN regardless of a cell reselection algorithm.
Accordingly, since a terminal is in a limited state depending on a network mode, until a GSM cell is obtained again due to PLMN reselection regardless of a cell reselection algorithm, an appropriate call originating and call terminating operation may not be performed, and a ping-pong phenomenon between a GSM cell and a WCDMA cell may occur.